1. Technical Field
This invention relates to impedance measurement apparatus and method. In one aspect, this invention relates to the design, construction, and installation of ground circuit impedance measurement apparatus in an underground coal mine. In one aspect, this invention relates to the design, construction, and installation of ground circuit impedance measurement apparatus in other industrial applications where accurate measurement of ground circuit impedance is required.
2. Background
In underground coal mines, as well as other industrial applications, medium voltage and high voltage electrical power equipment is commonly used. As an example, in coal mines, the portable, high voltage electrical power equipment is connected to an outside electrical power substation by lengths of high voltage cable with high voltage connectors to couple the cables together as well as to portable transformers.
In order to insure the safety of mine personnel, federal laws require that all high voltage underground equipment be installed with adequate grounding means to insure that the voltage on such equipment not exceed 100 volts in the event of a ground fault (30 CFR 75.001).